Center bootsplash on bigger framebuffers

In the JPEG decoder, use `bytes_per_line` instead of `width` for
address calculations, to allow for bigger framebuffers. When
calling jpeg_decode(), add an offset to the framebuffer address
so the picture gets centered.

Change-Id: I0174bdccfaad425e708a5fa50bcb28a1b98a23f7
Signed-off-by: Nico Huber <nico.h@gmx.de>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/76424
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Martin L Roth <gaumless@gmail.com>
Reviewed-by: Paul Menzel <paulepanter@mailbox.org>
Reviewed-by: Subrata Banik <subratabanik@google.com>

util/fuzz-tests/jpeg-test.c

@@ -30,7 +30,7 @@ int main(int argc, char **argv)
 	jpeg_fetch_size(buf, &width, &height);
 	//printf("width: %d, height: %d\n", width, height);
 	char *pic = malloc(depth / 8 * width * height);
-	int ret = jpeg_decode(buf, pic, width, height, depth, decdata);
+	int ret = jpeg_decode(buf, pic, width, height, width * depth / 8, depth, decdata);
 	//printf("ret: %x\n", ret);
 	return ret;
 }